It used to be that the only thing that determined whether a TV show was a success was whether folks actually sat down to watch it when it aired. And, starting in 1950, that’s what A.C. Nielsen and his eponymous company measured: using surveys and the audimeter, technology first developed to track radio listening, the company was able to find out which percentage of TV-watching homes were watching which channels at which times. That data helped networks and advertisers determine the success or failure of a show.

Now, however, who sits down to watch isn’t the only thing those TV gurus care about.

With that in mind, today Nielsen launched their first service to track which shows are being not just watched but also tweeted about, the aptly named Nielsen Twitter TV Ratings.

Nielsen and Twitter first announced their partnership last December, saying in a statement that the rating—developed on top of a system created by SocialGuide, a company acquired by Nielsen shortly before the announcement—would allow networks to complement viewership data with metrics to see which shows are driving conversation and engagement. The new data will bring Nielsen more up to date with the way people watch TV now, in theory helping networks get a better handle on who they’re reaching.

Because the shows that generate tweets are not necessarily the same shows that generate non-tweeting eyeballs—whether because of buzz-worthiness or audience age—more ways to count viewer engagement equals more ways for networks to show advertisers that their content is worth more money. The new service also underlines one way Twitter’s monetary power can be measured; as the New York Timespoints out, the prospectus for Twitter’s upcoming IPO contains dozens of mentions of TV.

Of course, Twitter has been around for years and people have been tweeting about TV for nearly as long. Nielsen has struggled in recent years to keep up with the new ways television is consumed (TiVo was introduced in 1999 but Nielsen didn’t introduce “Live Plus Seven Days” ratings until 2007; the company didn’t announce plans to measure streaming until this past February) and the Twitter TV Ratings have already been criticized as a tool for advertisers. As the Wall Street Journalpoints out, the number of people tweeting about TV has not yet been proven to influence advertising decisions, and only 30% of TV-related tweets are sent during commercial breaks.

But, only one day into the availability of these data, the Twitter TV Ratings are proving interesting—if not to ad buyers, at least to viewers.

In the week of Sept. 23–Sept. 29, Breaking Bad—unsurprisingly—proved strongest. More than 9 million distinct Twitter accounts saw at least one of the 1,237,900 unique tweets that were written about the finale episode. And Breaking Bad‘s dominance was by a large margin: the second-place winner (The Voice), ranked by that number of distinct accounts getting an “impression” about that show, had only a little more than a third of the audience that Breaking did. Competitions did well overall (two episodes of The Voice, one of Dancing with the Stars and one of The X Factor all made the top ten for the week), with a mix of shows rounding out the rest of the winners (one late-night show, an ESPN broadcast, two hour-long shows and one sitcom).

And fans of less-popular shows have reason to pay attention too. One quirk of the numbers is that each viewer of a less-watched episode or program has more individual power to affect ratings, compared to each viewer of a popular show: because the numbers measure both Twitter activity about a show as well as the number of people who are passively seeing those tweets, and because followers are more likely to overlap when there are more people tweeting, lower activity means that each individual follower affects the results more.

On average, the audience for tweets about TV is 50 times larger than the number of authors tweeting, Nielsen reports; in theory, a show with fewer, more-followed fans will have a much larger ratio, which means that a smaller number of authors can lead to a higher number of unique impressions. Too bad nobody told the fans of Lucky 7.